1. Field of the Invention
The present invention relates to compounds that act to block calcium channels; methods of using the compounds to treat stroke, cerebral ischemia, pain, head trauma, or epilepsy; and to pharmaceutical compositions that contain the compounds of the present invention.
2. Summary of the Related Art
The entry of excessive amounts of calcium ions into neurons following an ischemic episode or other neuronal trauma has been well documented. Uncontrolled high concentrations of calcium in neurons initiate a cascade of biochemical events that disrupts normal cellular processes. Among these events are the activation of proteases and lipases, the breakdown of neuronal membranes, and the formation of free radicals, which may ultimately lead to cell death. Several types of calcium channels, the L, N, P, Q, R, and T types, have been discovered. Each type possesses distinct structural features, functional properties and cellular/subcellular distributions. Type-selective calcium channel blockers also have been identified. For example, SNX-111 has been shown to be a selective N-type calcium channel blocker and has demonstrated activity in a number of models of ischemia and pain (Bowersox S. S., et al., Drug News and Perspective, 1994:7:261-268 and references cited therein). The compounds of the present invention are calcium channel blockers that can block N-type calcium channels and can be used to treat stroke, pain, cerebral ischemia, head trauma, and epilepsy.